Jonathan Is 194. His Cellular Power Switches Look Barely Used.

A giant tortoise of roughly 450 pounds (204 kilograms) hatched around 1832. He's called Jonathan. Inside his cells, the genetic controls for energy production show little of the disorder that age usually leaves behind.

He arrived on St. Helena from the Seychelles in 1882. That volcanic South Atlantic island sits roughly 1,200 miles (1,930 kilometers) west of Angola, and Jonathan shares the governor's grounds there with fellow giant tortoises. He is blind from cataracts. His hearing remains excellent.

With age, the chemical tags that tell genes when to switch on and off tend to drift into disarray, a process researchers call entropy. When that drift reaches the genes that run mitochondria, the tiny power plants inside cells, the energy supply begins to falter.

In 2017, a request to draw Jonathan's blood was turned down over concern for his health. The island's veterinarian was permitted to scrape a little tissue from inside his cheek instead. An international team led from Vanderbilt Health then pieced together his genome and its tags.

In genes tied to RNA processing and to mitochondrial function, those tags were strikingly orderly, the arrangement one might expect from a far younger animal. The researchers concluded that this tidiness partly shielded him from the slide that age brings. The work appeared in Science Advances.

How Jonathan kept his cellular switches in such good order remains unexplained. The team says it needs a blood sample, which would provide more complete genetic information, before treating the findings as settled.

Read the full story at Vanderbilt Health, October 7, 2026

Hot Take: Jonathan has received visits from generations of British royalty and outlived seven British monarchs. This esteemed elderly gentleman is entitled to a few secrets.